1. Field of the Invention
The present invention relates to a direct print technique for printing an image by directly connecting a digital camera or the like to a printer.
2. Description of the Related Art
A so-called digital camera direct print system has prevailed. In this system, a printer and digital still camera (to be abbreviated as DSC hereinafter) are directly connected via an interface such as USB or the like, and images saved in the DSC are transferred to and printed by the printer.
In the digital camera direct print system, each image file stored in the DSC is defined as a print designation file of a standard format called DPOF (Digital Print Order Format). The user designates an image to be printed as a DPOF file, and transfers it to the printer, thus printing that image.
In a communication standard between the DSC and printer proposed by such digital camera direct print system, transfer of image data from the DSC to the printer is made using an image file format such as JPEG, TIFF, or the like.
In recent years, the resolution of an image captured by a DSC has been increasing exponentially, and a DSC having a resolution of 16 million pixels is commercially available. However, even when image data captured by a DSC with such a high resolution is transferred in a JPEG format to a printer intact, the transfer is wasteful since the printer does not require image data of such a large size, depending on an image size to be printed. Moreover, for a printer with a small memory size, image data with such a large size may cause a memory overflow.
To cope with such situations, Japanese Patent Laid-Open No. 10-290470 and Japanese Patent Laid-Open No. 2003-134457 have been proposed.
Japanese Patent Laid-Open No. 10-290470 aims at reduction of the processing load on the printer. That is, the DSC executes decompression, color conversion, resizing, and the like of a JPEG file to convert that file into data of a printable format, and then transfers the converted data to the printer, thereby reducing the image-processing load on the printer.
In Japanese Patent Laid-Open No. 2003-134457, the DSC side corrects variations of the color reproduction characteristics for each printer to convert image data into a general image file such as JPEG or the like, and transfers the converted image file to the printer. In this way, a stable image can be obtained independent of the print characteristics of each printer.
Upon printing an image captured by the DSC, a print mode that designates a trimming frame is known.
In a “trimming” print mode, an original image is clipped, and the clipped image is printed to cover the entire photographic paper area based on “borderless” designation or the entire trimming-designated image can be printed based on “bordered” designation.
Also, a print mode that analyzes a captured image and applies brightness, contrast, and color correction processes to that image so as to improve the image quality is known.
Most algorithms for the brightness and contrast correction processes generate RGB and luminance histograms for the entire captured image, and analyze the histograms to correct an original image. However, upon making the trimming designation, an image is clipped and is transferred to the printer. Hence, the histograms change depending on the clipping position, and the brightness and contrast also changes.
In the “borderless” print mode, it is common practice to print an image to be larger than the photographic paper size without leaving any border. However, when an image is clipped, since there is no data of an area larger than the photographic paper size, an image of that area is cut off.
In order to solve the aforementioned problems, when an original image and trimming information are transferred to the printer, and that image is modified on the printer side, an unnecessary image part other than the trimming-designated image is also transferred, resulting in a low print speed.